Subjects

Exposure to cocaine and amphetamine structurally reorganizes excitatory neurons in the medial and orbital prefrontal cortices (mPFC and oPFC), inducing dendritic spine proliferation in the mPFC and eliminating spines in the oPFC. Modifications may be causally associated with addiction etiology. Certain cytoskeletal regulatory proteins expressed in the oPFC and implicated in postnatal neural development also regulate behavioral sensitivity to cocaine, potentially opening a window of opportunity for the identification of novel pharmacotherapeutic targets in the treatment of drug abuse disorders. Addiction is characterized by maladaptive decision-making, a loss of control over drug consumption and habit-like drug seeking despite adverse consequences. These cognitive changes may reflect the effects of drugs of abuse on prefrontal cortical neurobiology. Here, we review evidence that amphetamine and cocaine fundamentally remodel the structure of excitatory neurons in the prefrontal cortex. We summarize evidence in particular that these psychostimulants have opposing effects in the medial and orbital prefrontal cortices ('mPFC' and 'oPFC', respectively). For example, amphetamine and cocaine increase dendrite length and spine density in the mPFC, while dendrites are impoverished and dendritic spines are eliminated in the oPFC. We will discuss evidence that certain cytoskeletal regulatory proteins expressed in the oPFC and implicated in postnatal (adolescent) neural development also regulate behavioral sensitivity to cocaine. These findings potentially open a window of opportunity for the identification of novel pharmacotherapeutic targets in the treatment of drug abuse disorders in adults, as well as in drug-vulnerable adolescent populations. Finally, we will discuss the behavioral implications of drug-related dendritic spine elimination in the oPFC, with regard to reversal learning tasks and tasks that assess the development of reward-seeking habits, both used to model aspects of addiction in rodents.